1. Field of the Invention
The present invention relates to a three-dimensional visual sensor for measuring position and orientation of an objective workpiece by projecting a reference beam such as a laser beam onto the objective workpiece and receiving a reflected beam with a camera.
2. Description of Related Art
The three-dimensional visual sensor for measuring the position and orientation of an objective workpiece by projecting a reference beam such as a laser beam onto the objective workpiece and receiving the reflected beam with a camera is used broadly and generally. Regarding the reference beam, various types such as a spot beam and a slit beam are known. Also regarding the beam projecting means, various types such as a type having two light sources and a type which scans an objective workpiece with a single light source and thereby produces effects equivalent to the effects produced by the type having a plurality of light sources are known.
Also, a visual system which detects the three-dimensional position of an outline of an object using an image capturing device for capturing a two-dimensional image and a three-dimensional position measuring device using a slit laser beam is known (for example, JP 60-183509 A).
In the case in which an objective workpiece placed at a predetermined position is measured with a three-dimensional visual sensor to obtain data on the shape of the objective workpiece or examine the objective workpiece, a reference beam such as a laser beam from the three-dimensional visual sensor can always be projected onto the objective workpiece and required data can always be obtained. However, in the case of an objective workpiece of which the position and/or orientation on a plane is not settled, or an objective workpiece of which the three-dimensional position and orientation are not settled like workpieces stacked randomly, when the position and orientation of the objective workpiece is measured with the three-dimensional visual sensor, it cannot be determined which part of the objective workpiece the reference beam is projected on, or even whether the reference beam falls on the objective workpiece or not. Thus, the position and orientation of the three-dimensional visual sensor needs to be adjusted so that the reference beam will be projected on an intended part. However, there is no three-dimensional visual sensor which can perform automatic adjustment, which forms an obstacle to automation of work.